Acoustic device



July 14, 1931. A. JFLECK ACOUSTIC DEVICE Filed Dc. 15, 1928 3 Sheets-Sheet 1 BRHAM J. FLECK %y %a &Lumme/L;

July 1'4, 1 931; v A. JS'FLK 3 9 ACOUSTIC DEVI CE Filed Dec. 15, 1928 3 Sheets-Sheet 2 Suva Who@ ABRAHAM J. FLEK.

` 3 Sheets-Sheet 3 A. J. FLECK AGOUSTIC DEVICE Filed De.

'July 14, 1931.

umenica ABRAHAM 3 FLECK. & &tkom Lu I {TE E TENTO FIE; 7?

d ha member, which s oined' gg age, then thas elea mundim# &m-na mem-mor ulkyh fi n h mat rial I a o tute, such as aluminum or its alloys. Those materials should be chosenwhich have Very little;frequencylresponse of their own. i

`For the cliaphragm it is preferred to` use hard seasonecl Wood such as isused in Violins and thelike. HoweVer; the diaphragm may also be' eonstructed fromfthin metal -alloys, mica or any other material having the requisite Vibraton bharacteristics. The. dia- 25 e "of metalsof a non-yihratory naturegas bake.

phragm should *be maole as thin as is ,commensurate 'with thej-;resiliency required* to maintain its plane andto withstancl vibration* `stresses;

The back portion of the chamber may be 'made of the same'kincl of material as the fdiphragm, and preferably is'provideclwith stripsofmaterial Secured to it ancl extendj ingfeliagonally across `"its externaljaree.

H hese st'ips may be Cementedor otherwise "suitably securedtotheback.

The sides" of the asng are made up of mterial which is preferablyof non-Vibrating charz'o'teristics.` This' may comprise a heavy' Wood edgel With a thiek ho rcler or gasket of lead, or the borcler orsicle's may consist lite, hardrubber or. the like ?There are `a "wide number of i substnces whiehfmay 'be employedto subserve thefunotion of this member, that is to say, to provide a i base' for the "chaphragm which 'will checkfthe path otth'e Vibratio'ns; s`o as to reteinlthe vibratins within'thediaphragm. Thusjthe mechancl transmissi'on offth'e `vibrzitions ischecked at the borcler'lof the'clia ph ragni,

` [.In 'eonstruoting jthejpreferrecl device, the

4 sound;` apertures in` the diaphragm, bottom `and si cles are preferbly `so"lpo`sitione`d that eachap ertulje is opposite a solitl su faee, that *is to say, thefapertures are imaljigned with frespectto 'ezich oth`er.` Thisgty'pe f "construction while insuring substantial airipli fiettion, preelucles -ex'eessive reverberation of souncls,; and "`s ubstntially eliminates `'consegqjuent j distortioii and re cluetion 'offgualitya of the emanating waves. r i

i 'j I "of derjto Tender theintention more ioln pre en sibleg there are shown I preferrecl ema*** bodments oEfit j in the "accompanying' dr ln'gv`- fings.` In thesedrtwings the sme referenfee ``I iimerals refer ,to similar, p

" :the`several`views, ofwhichf* i i 5 od in tlienyeriton; i i e p aiiig is a rearview thereof;

gFig. 3 is aflongituclinal section oli-the gFig; 1 isa front View' of en emplifier emvice shown 'in Fig 1; i i ;Fig is a side View illustrating the juXtaposition of the sound: openings in the sides of `the casingg i e "1 gFi g isnend View similartoFig. &illustratng'the prineipleof unaligned openings; ;6 is anelrgeiddetail-of the yibra tOntriiSmttngclevice;

t th h `t i *roug 1nbefore,`-may beof ;my desi-red shaperoonjfiguration; provide& only, howeve'r, that their F ig. 7 is cross-seetional yiew of the device'shown in Fig.` 6; i i i Figs. 8 and 9 areplan and elevetion views, i

respeotiylyf, of a modified form of vibration Fig. lOjis a modification of the leyice in transmitter; i v

which .a single vibratng means is assoeiated with a plu'rality ofcasings;

Fg. l l is a; further modification emboclying i 75 i a nultiplebridge Vibration trensnitter; Fig. 12 is a sicleyiew partially in section thetcleviee shown in'Figg 11; and e of superimposecl easings; e y

Refrrng to thedrwings; 'and particularlyto Figs. 1 to 6 thenovel amplfyin gdeyicecompri'ses a easing having& diep hragm top l, bottom section' 2,' and sidewvalls 3. iTheicising mLybe made upinr'an desired shape, the rectangular form` shown in the drawings-being-merely typical aiid prefertable. Th,e top, or -cliaphragmyas inclited i herei'nbeforemay comprse asuita'ble' sub- {i stance'. having the clesred charaoteristcs of) strength, thniess and vhraton. Ths memsounl openings to' Permit the emission of m plfied sound lwzw'esi As shown these maybe of any desrecl eonfigurzvtom sueh s the cirv --Fi`g. 13 is a cross-sections& ele'vtion o ta further modification 'embodying a' plurz lity phragm is preferably provided With` anen-f largedeentral aperture` -(se` e Fgs. Ia'ncl 5); 3

It will be `understood tha-ta suitable treme or 4 'guerdor coyering maybe placed oVertheym claphragmf if cl'esirecl' for purposes of pro i tecting or covering the same. i

The` bottom section-; which eomposecl of thedescribed materials', u in a "manner similar to the Construction` of the i 1 5 diaphrztgm, 'is formed j with a plurajlity 7 of openingsf and& "The larger peningsfl-it -willbenotecl are positioned 'near the central portion of the asingwhere the larger Volume struightimiplanar free 'path of the Vibrations through ?thei two*` members is permitted.

These openings, es has heeh` Iindioatecl herepositions eonform to the" 'requirements noted. Prefera'bly' the bottom section isa-provided H i .with suitable strips ll which aid in providfjsound obtains; It ;will be ohserveclon the 'uo inspection of Figslencl 2, thatthe openngs rin` the bottom set'ion areuiialigned with the.

apertisinth top oricliaphragm,so thatno iso 1 ing a proper soundpropagetingjbottom ;sei tion ;Suitable gasketsl of lead felt-or any other suitable nonvibrateblemterial are 'iiii trodueed between the botton*section 2 'ariti The various sizes and positions of the the rreme `-3 `betweeirth`e'; frame 3 'and ;the diaphragm l topreventfthe mechaniol -trnsmissionof the sound wavs away" from i thediaphragm;

iso'

r i mem-4 i epeningeane important in aiding in the prep".- i er" tuning ofthe instrument, and it has been found desi-rabit; to usually` locate theopen- -ings o thatthey are not oppositeeach other( many instanees; it is] found that there; is

*af range the pzoper depth of thickness, ot` distance between the diaphegrn and the bot tom of the ?speaker- Where the refleeted echo is of maximum amplificetion, alnd it found thatthis ditanceis contingent in most ini stanee on the area of' the di ph agm andjthe Stress of the Vibrations. i

-The i sides of' the easing ane likewiseflprdr v -icleeil with ai plurality of openings 9 and 10. t Asjobserved herein'bjefore these ere so po itione tlmt'the prolongationof the eent'il n axije of` each apertui'e: andthe arallel"p e-` i *jectiens mm the peripheres thereof do not i jinte cpt similarpr ojections of the 'apertnre `en the opposed sides;` AS noted above," this i eo'nst 'etion ineures maximum amplification" whfle preventi-ng -phae displacement of the sound wavesand tes lting distoi tion.

The bettonij` mefnber 2: may i be provided with a ber l lfor supportingfthe vibi ating mea s; when s eh" unit is mounteci within the asm This vb atng means may be of any suitable "Construction including electromagnetic and eleetodynamie units. i i i i 'As intiinated hei 'ei ibefore, vilretions me 'adapted &to n be impai'tedito the diaphragn over a larger a 'ea therof then that of the ciitout top'esent a plii-elity of? apertiires tached to the source of vibrationsgies jone X-L pem a Jnd evenfffep odnetion. i i i z 35 To `per-mit this attaehment: of the l bridge, i and: a tflthe' 'same time to provide-ethe spaced i i-elationshi p.` dsotibedaboye, the oetinemn i bers; 18.` are J employed. Asi` shown, "particulrly; `Fig: 7, `these; comprise a flat "portion :19, and integral downwardly sextensiene20 and e teiiminal foot 21." w'Ihe top `sind `foot sections" me bored to permitstheflpassage. of H seeuning means ifllustrted eonventionel ly by of s these arms allowethe desined spzicedfi relationship ubetween the: di-a phnegm and the point, giving; et" i once in incr easedii Volume',

able pathifor thegtnanmissien ofmib ations from the bt-iclgetoza wdenareei of thwdiar phragm. i

` While the been deseriezi,`cemprises a plalitywof sepaate membeii which ane z dapted tosbesec red i together it willbe pp eeate tthet thebmay ini tiziliy be madennpne a inglennita y `&e- Nice; i Smeh: a structure-isishownxin Eigs; `8

and` 9. This comprise emember having a; pl n alityf of md ial arms 24, extending wardly and` convergi ngjatl a; eentsai portion 1 The central` portion; whiehnitflsill' be noted; iis sipase& ebovethe freeuends of the `rzuilial` arms, `is` Provided- With` aymeanisf 26 through which the trenmitter may be'a'sseciatedi with a Vibiato-y` element.` rThe leme! ende of the" arms! i'eextended anguiarly so i i their free` end'sso astopenmita Wide Spacng wavestotheexterior mediumi:` i i i i (Lan em- 1 tion is no means limited to such a s'tzliesb'oth directions), aire simplified; by impressd within? ones of the easings: upon the! ban Mi;

that upon asemblanee, they-:he iithe` same i plane as the diuphra gm. i 'i hesef'ree ende: ere ;suitably `&perm -ed se as te` receive the;semin-` ingmeanQT. showmthe ediabarms :me eonstnieted: between thexcentmlpottionsrand maybe "accentuatedi by using a multiple con struetion 'as is shown in Figs ll andq12; W ith" this Construction, thevibrations from' the vbratng member are transmtt'ed to the diaphragm over avery* Wide areaQIt` vvill' surface is 'dire points of i attachment between the upper and intermediate bridges.. i This structure is bene-` ficialin promotinga more uniforma distribu- 'tion of stresses and resulting" vibrations of the [several 'members,-jby providing, in fact 4 a uniplanar* vibratng'nember whose' entire i tly responsive to the imposed vibratons. 4

If desired,"the volume of ainplfied "sound maybe urtherjappreciably increased, by

associating with a single "vibration" trans i -mitter a pluralty of propagation chambers.- As a typical example', thismay'take the form shown in Fig. 13.` This comprses apluralty ofpyramided chambers 38, 39 andtO, each of i' ,whchis constructed according to the general prjnciples descrbedl 'abovei Their upper chamber 40 is provided With a vibrating bridge associated in responsive relationto a source: t of vibratonss The intermediate chamber abuts: thenpper chamberso that the saperturesain its top: section register With those in the bottom portionofchamber 40.

Similarly. the lowermost chamberflabuts'the `'intermediate chamber so that the apertures i in their` contiguous `faces are in registration.

i It Will beseen that vibration of the dia- .phragm of the upper chamber :win cause compressions .and rarefaction ofthefair in the several 'chambers below,'an d thatthe :normal placement of the' sound openings in 1 theseveraljohambers 'are's balancedthat &the amplfied sounds emitted with full ed'to amplify` sound ?Waves whle 'allowing any undesirable results. i\ l u i ..vlt -willn also be :noted thatthe preferred construction hereindisclosed provides an r independentlv pe ated dia phragm in 'that fthe diaphragm isnot a subj ect:.to vibrations r mech anica lly transmitted from the board" 5 nor `the hame'. Likewise the vibrations of i the diaphragm arenotjmechanically trans `mittedto thetreflectingboard;nortoi the V :fl-ame: The insulation againstwmechanical `*transmission .of 'the a vibrations s preferablv i accomplshed *by insulatng thefdiaphragm the refiecting board, .andthe vibrations trans- ;in the preferred Construction' the Walls of ;bedrectly reflected back and fissne through -the op`e`nings While other of the sound waves e g, issue fromthe chamber byreason' of their her ein shown and' described, :except assuch from the remainder ofthe Speaker by lead or `other type gaskets' as described above. The diaphragm,; however, cooperates Withl mitted through'the air, and thus thewhole assembly Ior unit produces a ino'st satsf actory and true reproducton of thesoundj lt "Will ?further be notedfroni thepreferred con-4 `struction heren that, thevibrationsl pro'- duced by the` driving unit, WlllCl s ;usua'l1y i"- electrical, 'are `applied to the diaphragm `at i a point or a plurality of :points which are 'spacedapart or awayfromthe actual "center i of the daphnagm. It 'Will also be noted that .the chamber areusually: constructed so that they are in parallel' 'elationg o eachother.

This the i diaphragm lSy usu'allv pai allel to the bottom and some ofthesound wavesmay g Whn certainr' odifications h vlbn d'escrbed in detail, it is to' be'understoodthat these are given'merely by Way` of example,

andgsnce the underlyingprincples *maybe mcorporated in otherspeclficmechansms, t is not intended to be restrcted tothe ones restrictions are clearly imposed bythe appended clams. i

j l/Vhats claimed is; l

member beingin unaligned 'relationship t i sound amphfy-ngydevce `ncludng a sound I propagatmg i chamber `'havng "apertured top` andbottom sections, the apertures. i f in the sections' being injunaligned relajtioi- 111 ship, a bridge member Secured to theg top' section, 'and `meansto;imp`art` vibratons to r i .the bridge v 4 W r *for free, natural, multi directonal. dfiusion and/Ori refraction. !By .the novel i construoi tion of the vibrator in conjunction iththe g other. parts, maximum use is madeof the 4 capacity ofthe chamber Without -iitroducing aratus com- A prising asoundpropagating chamberinlud- 5 ng top, bottom and side;` sections, each ?of 'WhlCll -1s !provided With ai pluralty of 4 aper-" tures, the apertures presenting a' non-uniplanar j path i through, any two aperturesi ;4, A sound 'amplifying device including '1 a sound propagatng chamber having top and bottom aperturcd sections, the aper- 5. A sound 'amplifying apparatu'scomprising .asound propagating chamber con: sttntng a casngfncludng top, bottomand `'sde sect ons,the topr central section being V ing a sound propagating chamber including the disc.

v from the vibrating means to the top section.`

I part vibrations thereto.

formed with a large aperture, a vibration transferrng member securely attached to the top section and bridging the aperture, and

means Secured to the transfer member to im-` 6. A sound amplifying apparatus includa top vibratable section which is for-med with an aperture, a diaphragm disc in the i 1 plane of the apertureand secured tothe top section, and means to impartvibrations to 7. A sound amplifying apparatus comprising a sound propagating chamber having a top section formed with an aperture, an

apertured disc attached to the section and in substantial alignment with theaperture, and

means to attach the disc to the top section, whereby` a free path is permitted through\` the apertures in said disc and top section.

S, A sound amplifying apparatuscomprsmg a vbratng means, a dsc connected jto said means, a sound propagating device comprsng a pluralty of supermposed rea sounding chambers, and means to mount the vibratngmeans and disc within the chambers. a 4

` 9. A sound amplfying device comprising a sound propagating` chamber having `apertured top, side and bottom sectons, each section being formed with apertures which are ofl'set with respect to the apertures in another section, a vibration transferrng bridge member attached to the top section and formed with a central aperture; a second vibration` transferring bridge Secured to the first bridge and formed with a central aperture, whereby a free path is provided through "the apertures in the bridges and" top sections;` and i means to impart vibratonsto the last named vibration transferring bridge.

10. A sound amplit'ying device comprising a sound propagating chamber, including top, side and bottom apertured sections, each of which is for-med with apertures which are non-aligned with the apertures in another section; a vibrating means spaced above the top section, and means to transmit vibrations 11. A sound amplifying device comprising a sound propagating chamberhaving an opening in the top section and a vibration the apertures in the top, bottom and sides of each section being unaligned; and means to impart vibrations to the top of one of the sections.

14:; A vibration transferring bridge of the class described comprising a plate having a plurali-ty of apertures therein to permit the passage of sound waves, and a plurality of 1 rigid arms attached to the plate and extending laterally therefrom.

15. In a sound reproducer a vibrating i member, a reflecting board, a supporting frame mounted between said vibratory member and said reflecting board and associated With each,and vibrationless means interposed between said vibrating member and` said frame to prevent the mechanical transfer of sound vibrations.

16. In a sound reproducer, a vibrating diaphragm, a sound refiecting board associated With said diaphragm, insulated means between said diaphragm and said board for preventing the mechanical transmission of vbrations from one to the' other, and a bridge member assocated with said diaphragm and afixed `thereto at a plurality of points spaced apart :from the center of said diaphragm for transmitting to said diaphragm vibrations produced by a suitable driving unit.

17.` A vibration transferring member of the class described comprising a single member having a central section, a plurality of rigid radially extending, spaced arms, a vimeans attached to the section and bridged across and spaced from the opening.

12.' A sound amplifying device' comprising a a' sound propagating chamber having an opening in the top section and a vibration means attached to the section andbridged across the opening. i

i 13. A sound amplifyng devicecomprising a plurality of superimposed resonatin chambers, each chamber having aperturec l top, bottom and side sections, the apertures in a the top of one section being aligned with the apertures in the bottom of the section above; 

